This invention relates to a combinatorial weighing apparatus capable of combining and weighing out articles.
A combinatorial weighing apparatus known in the art operates by measuring the weights of articles loaded into a plurality of weighing hoppers, selecting a combination of the articles giving a total weight closest to a target weight value, discharging only the selected articles from the weighing hoppers, subsequently reloading articles into the weighing hoppers whose articles have been discharged, to prepare for the next weighing cycle, and then repeating the foregoing steps so that an automatic weighing operation may proceed in continuous fashion.
The combinatorial weighing apparatus of the foregoing type has a charging hopper disposed on the central portion of a base, the base having an upper surface which is circular in shape, and a distributing supply device extending radially from the center of the base, provided at the lower end of the charging hopper, for transferring articles, discharged from an outlet port located at the lower end of the charging hopper in order to weigh the articles. A plurality of weighing stations are provided on the circumference of the circularly formed base, each weighing station including a weighing hopper and a weighing device for measuring the weight of the articles introduced into the weighing hopper from the distributing supply device. After the weights of the articles introduced into the weighing hoppers of the respective weighing stations are measured, the apparatus finds a combination of articles having a weight closest to a preset target weight by performing computations based on the measurements obtained, opens the weighing hoppers corresponding to said combination and collects the articles discharged from these weighing hoppers in a container disposed below a chute, the upper end of the chute receiving the articles directly from the weighing hoppers.
With the combinatorial weighing apparatus having the conventional construction described above, the circular configuration of the base necessitates not only a large installation area but also considerable space about the entire circumference of the apparatus for inspecting the weighing stations which, as set forth above, are arrayed on the circumference of the base. Another disadvantage is that it is impossible to combine a plurality of these combinatorial weighing apparatuses so as to, say, have each apparatus weigh out articles of a kind different from those being weighed out by the others and package the resulting articles in a single pack.
Another problem with the conventional combinatorial weighing apparatus is that, as the weighing operation proceeds, the articles supplied do not always flow in an orderly manner or may be introduced into the weighing hoppers in an amount which is more than that expected. In either case the result can be an unsatisfactory weighing operation, such as weighing out more of the articles than intended. In one arrangement of the conventional apparatus, therefore, articles which have been weighed improperly are discharged into a packaging container which is then removed from the apparatus. This means that the operator must go to the combinatorial weighing apparatus to remove an improperly weighed batch of articles whenever an abnormal weighing operation occurs, and that normal weighing cannot proceed until the container is removed. The overall result is a decline in the efficiency of the weighing operation.
Still another shortcoming encountered in the prior-art combinatorial weighing apparatus, specifically in the distributing supply device thereof, is a variation in the flow rate of the articles as they travel along the troughs of the distributing supply device in the process of being supplied to the weighing stations. When weighing is performed under such condition, a frequent occurrence is an improper weighing operation or one in which more articles are weighed out than intended. Again, the result is poor weighing efficiency.
A further disadvantage possessed by the conventional apparatus is that since the weighing stations are disposed on the circumference of the base, a hopper drive mechanism for driving a weighing hopper and associated pool hopper must be provided for each of the plurality of weighing stations.